Studies on haemorrhagic septicemia associated with hafnia alvei in some freshwater fishes

الملخص EN

A field survey was carried out to investigate the prevalence of Hafnia alvei (H.

alvei) in commercial fish farms [Oreochromis niloticus (O.

niloticus) and Clarias gariepinus (C.

gariepinus)] in kafr El-Sheikh Governorate during 2000-2002.

Eleven suspected fish farms, were investigated.

Affected fishes showed abnormal swimming, sluggishness, darkness of the skin, anorexia, haemorrhages and sudden variably high mortality up to 21.9 % with a haemorrhagic septicemic picture .

Bacteriological examination revealed H.

alvei with a percentage of 8.2 % and 9.5 % in O.

niloticus and C.

gariepinus , respectively.

The antibiogramme of the isolated strains was investigated.

Histopathological examination was carried out for both naturally and experimentally infected fishes.

The pathogenicity of the isolated H.

alvei strains was studied and caused mortalities in tested fishes following intraperitoneal injection with the LD50 values ranging between 1.3x104 and 2.5x107 bacteria fish-1.

These values were considered to repressnt a high to moderate degree of virulence.

This study is considered the first record of H.

alvei infection in O.

niloticus and C.

gariepinus fishes.